Air bag systems for protecting passengers to prevent injury to the human body during automobile collisions have been developed as far back as the mid 1960's. By the early 1970's, enough testing had been completed to prove the feasibility of the air bag and the current process and design standards were adopted. Air bag systems are now standard equipment in most of the new vehicles on sale today.
The air bag system comprises a sensor or a plurality of sensors for detecting a collision of the vehicle, a gas generator or inflator for expanding the air bag in response to a signal from a sensor, and an air bag expanded by the gas generator for absorbing any shock imposed on the passenger during the collision.
The air bag has a hollow portion for receiving the gas, an opening for attachment of the gas generator, and a mechanism for venting of the gas from the air bag after expansion to provide the collapse of the air bag and the cushioning of the passenger. Various designs of venting mechanisms have been developed which include a vent hole and/or the use of the permeability of the fabric of the air bag. In order to partially or fully restrict the permeability of the fabric of the air bag and for the reinforcements of the stitched portions of the seams of the air bag, a coating may be provided on the fabric of the air bag.
The prior art manufacture of air bags normally involves initially preparing a woven fabric utilizing a high strength synthetic fiber; cutting two or more pieces of this woven fabric into specific shapes; binding, sewing or gluing the peripheral edges of the various pieces of woven fabric together; and subsequently providing the opening for attaching the gas generator and providing for the gas ventilating mechanism. Once manufactured, these bags are assembled to the gas generator, packaged and shipped to the automotive assembly plants for assembly into the finished vehicle.
While the above prior art process has undergone numerous refinements over the past 20 years, the concept has remained basically unchanged. The above prior art process is an expensive labor intensive process using expensive materials with little opportunity for significant cost reductions. The air bag which is produced is a somewhat heavy bag which is stiff and therefore difficult to fold and compress into a small package to facilitate the assembly of the air bag into the vehicle. In addition, the multi-piece fabric which is used in the manufacturing of these prior art air bags produces an air bag which includes seams which are susceptible to gas leakage and, the fabric itself presents somewhat of an unfriendly abrasive surface to the passenger of the vehicle when it is inflated.
Accordingly, what is needed is a design and method of manufacturing an air bag which lends itself to automated production using relatively low cost materials. Ideally, the new design of air bag and its associated method of production will produce an air bag which is lighter weight, seamless and significantly lower in cost than the current design level of air bags. The new air bag will be lighter is weight, easier to compress and able to solve the other problems associated with the prior art air bags.